Production of a nonwoven fleece of continuous filaments

ABSTRACT

Process for the production of a nonwoven fleece from continuous filaments of a spun and stretched polymer yarn, especially a yarn composed of continuous hollow tubular polyethylene terephthalate filaments, wherein the yarn having permanently crimped filaments with an individual denier of about 0.5 to 20 denier is subjected to a temporary elongation within the range or region of the stress-strain curve which produces an elastic strain but under a load of at least 0.1 grams/denier, the permanent extension or set of the filaments being less than 4 percent, and then releasing the tension on the yarn whereby the crimped structure of the filaments is reformed and the yarn spreads out laterally. The resulting product is useful as a filler material in pillows, quilts, jackets and the like.

United States te Inventors Helmut Werner Appl. No.

Filed Patented Assignee Priority PRODUCTION OF A NON-WOVEN FLEECE OFCONTINUOUS FILAMENTS 13 Claims, 3 Drawing Figs.

U.S. Cl 28/72, 28/ 72.3

Int. Cl D04h 13/00 Field of Search 28/72, 1,

INITIAL CRIMPE D YARN Primary Examiner-Louis K. RimrodtAttorney-Johnston, Root, O'Keeffe, Keil Thompson &

Shurtleff ABSTRACT: Process for the production of a nonwoven fleece fromcontinuous filaments of a spun and stretched polymer yarn, especially ayarn composed of continuous hollow tubular. polyethylene terephthalatefilaments, wherein the yarn having permanently crimped filaments with anindividual denier of about 0.5 to 20 denier is subjected to a temporaryelongation within the range or region of the stress-strain curve whichproduces an elastic strain but under a load of at least 0.1grams/denier, the permanent extension or set of the filaments being lessthan 4 percent, and then releasing the tension on the yarn whereby thecrimped structure of the filaments is reformed and the yarn spreads outlaterally. The resulting product is useful as a filler material inpillows, quilts, jackets and the like.

Patented A ril 13, 1971 2 Sheets-Sheet 1 mvwv'mus: HELMUT WE RNER H AN SSTA P P BYE Patented April 13, 1971 2 Sheets-Sheet 3 FLEECE WEB FLEECE'vsas IN VHN'IUKS. HELMUT WERNER. HANS STAPP ATT'YS PRODUCTlON OF ANON-WOVEN FLEECE F CONTINUOUS FILAMENTS Cushions, pillows and quiltedarticles, such as quilted blankets, anoraks and the like have beenfilled with nonwoven synthetic fibrous fleeces consisting of staplefibers and also with nonwoven fleeces which consist of endless orcontinuous filaments. Such fleeces of continuous filaments arepreferably manufactured by spinning a synthetic fiber-forming polymerfrom multiapertured spinning heads so that the filaments, preferablyafter being drawn or stretched, are accumulated on a suitable base orsupport means. Texturizing or bulking of the filaments is usuallycarried out either by subjecting the filaments to a turbulent blowing orby applying an electrical field before collecting the filaments into afleecelike web.

One object of the present invention is to provide a voluminous fleece orfiller which can be used for filling cushions, pillows, or the like andwhich are nonwoven fibrous webs or planar structures, preferably made upin layers or in the form of a coil or roll..ln particular, it is anobject of the invention to provide a process for the production of anonwoven fleece composed of continuous fiber-forming thermoplasticfilaments by using an initially spun and stretched yarn in which thefilaments have already been given a permanent crimp, preferably bymechanical means'such as a conventional stuffing box. Yet another objectof the invention is to provide a process for producing such a fleecewhich is easily carried out and which produce a novel effect inlaterally spreading out the crimped filaments into a more usefulnonwoven sheet or web of crimped continuous filaments. Other objects andadvantages to the invention will become more apparent upon considerationof the following detailed description of the process of the inventionand the product achieved thereby.

It has now been found in accordance with the invention, that a valuableimprovement can be achieved in a process for the production of anonwoven fleece from continuous filaments of a synthetic fiber-formingpolymer if the initially spun and stretched yarn made of permanentlycrimped individual filaments having an individual titer of 0.5 to 20 andpreferably about 3 to 8 denier and a crimping are number of from 50 toI50 and preferably about 65 to I20 arcs per l0 cm. is subjected to atemporary elongation sufficient to bring the individual filaments withinthe range of elastic strain under a load of at least about 0.lgrams/denier, and the tension on the yarn is then partially orcompletely released but to an extent sufficient to reform the crimpedstructure of the individual filaments and to permit the yarn to spreadout laterally. In general, the load producing the required elongationshould amount to about 0.1 to l g./den., depending upon the particularsynthetic filaments, i.e., after relaxation of the tension, should beless than 4 percent and preferably'less than 3 percent.

When it is desired to produce very bulky and voluminous nonwoven webs orfleeces, an extremely advantageous initial yarn is one composed ofpolyethylene terephthalate hollow tubular filaments which have a hollowvolume of 10-30 percent, preferably 12-25 percent, with reference to thetotal volume of each individual filament, i.e., each filament preferablyhas a uniform annular cross section with the hollow central portionbeing not more than about 30 percent of the total cross-sectional areaof the filament.

The expression range of elastic strain" should be understood throughoutthis specification and claims to mean that region of the stress-straincurve which extends up to a specific load value of the individualcrimped filaments, this load value being that at which an identical butuncrimped yarn exhibits a permanent extension below 4 percent. Thiselastic elongation," i.e., that increment or region of elongation wherethe filament remains almost completely elastic except for a small amountof permanent extension. The optimum loading and with it the degree ofelongation, varies for different types of polymer filaments, but may bereadily determined by a few preliminary tests. This optimum effect isachieved for purposes of the present invention when the yarn or tow ofcrimped continuous filaments, after a temporary elongation, spreadsapart to form a nonwoven fibrous web or fleece of maximum width. Themaximum specific loading may be considered to be the load value at whichthe crimp of the yarn, after removal of load, still just reforms orsprings back along the yarn. However, it is generally advisable to keepthe load below this maximum loading value.

When using polyethylene terephthalate filaments, the temporaryelongation is preferably carried out using such a load that thepermanent extension or set produced in the yarn is less than 3 percentand most preferably less than 1.5 percent. However, the load must be atleast Oil g./den.

With polyethylene terephthalate tubular filaments which have anindividual filament titer of 0.5 to 20 den., preferably 3 to 8 den. anda crimping arc number of 60 to 150 per l0 cm., preferably to l50 per l0cm., a load of 0.1 to l p/den. has been found satisfactory and producesadequate results; however, by using a load of about 0.5 to 0.8 g./den.,extremely good results can be obtained. Continuous linear polyesterfilaments and particularly polyethylene filaments which have been spunin a conventional manner to provide a hollow tubular structure, e.g.,with a hollow volume of l030 percent, preferably 12-25 percent, asdefined above, may have a relatively wide range of crimping arc number,depending on the end use of the fleece. For example, as a fleece forfilling cushions or pillows in the form of a coiled or layered web orthe like, it is sufficient to provide a permanent crimping of thesehollow tubular filaments of about 50 to l20 arcs per 10 cm., preferablyabout 65l00 arcs per 10 cm. When used as a voluminous fleece for fillingquilted articles, e.g., in the form of a single sheet or web of fleece,these same are numbers are also quite suitable. Such crimping can bereadily produced by conducting the initially spun and stretched hollowtubular filaments through a conventional stuffing box.

The process and products of the invention are not limited, however, tothese initial polyester materials. If the nonwoven fibrous webs orfleeces are to be further processed in order to produce a liningmaterial or insert of minimum thickness or a nonwoven textile fabricwhere the bulk or voluminosity of the web is less important, then yarnsor tows made from polyamides, polypropylene or other syntheticfiber-forming polymers may also be used to great advantage. The chemicalstructure of the polymers being used, including stereoregulation, andany pretreatments to which the filaments have been subjected duringtheir manufacture naturally have an effect on the process. Thus, forexample, the spinning conditions, the nature and degree of the drawingfor molecule orientation and the crimping to which the filaments havebeen subjected affect the final product. These factors must beconsidered whenselecting the process conditions and when tryingtoproduce certain properties in the final product.

However, the broad ranges recited herein are generally applicable to allsuch fiber-forming .polymers, and by following the specific elongationand relaxation steps defined herein while carefully controlling theamount of load during elongation to avoid exceeding the elastic limit,one can easily determine the optimum affect in terms of producing amaximum width or spreading apart of the fleece web or band.

One important influence on the process according to the invention is thedegree of crimping, i.e., the number of crimping arcs per unit oflength. It does not matter what kind of crimping is used or how thecrimping has been obtained. For example, yarns crimped in a stuffingbox, which exhibit a so-called two-dimensional crimp, are especiallyuseful, but the process may also be applied very successfully tofilaments which have a three-dimensional crimp. Such filaments or yarnsare obtained, for example, by spinning two chemically or physicallydifferent polymers using special nozzles, to produce so-called-compositethreads or filaments.

The individual filament titer or denier may vary within relatively widelimits and must ordinarily be chosen to suit the intended application orarea of utility of the fleece. Likewise,

terephthalate the choice of initial filament materials depends on theend use of the fleece. Very good results are obtained using threads orfilaments of all types which have an individual filament titer of 3 to 8denier.

The spreading out or lateral separating effect is most stronglyinfluenced by the degree of elongation which, according to the processof the invention, must take place in the region of elastic strain butunder a load of at least 0.1 g./den. At the lower and upper limits ofthe region of elastic strain or the amount of loading, the spreadingapart of the crimped filaments is usually only slight but a temporaryelongation within such limits is still reasonably within the scope ofthe invention in terms of a distinguishing effect.

When the loading force tension of the elongation acts on a yarn ofcrimped filaments, the crimp first disappears" by becoming latent andthe yarn as well as the individual filaments appear to be almost smoothbefore the filaments are subjected to the elongation or elastic strain.It is desirable, prior to the device which elongates the yarn within theregion of elastic strain, to arrange an apparatus in which elongationmay take place predominantly within the region of crimping elongation,i.e., simply to straighten out" the crimp. For example, conventionalbraking devices are suitable for this purpose.

The width of the nonwoven web or fleece which is produced depends,naturally, on the number of individual filaments of the yarn or twobeing used. This number of individual filaments, depending on thepurpose for which the product is intended, may be for example between3,000 and 30,000 or more.

The process is not limited to the use of any specific apparatus,although devices in which the elongation of the yarn is accomplishedbetween triple or quadruple rollers, i.e., a series of draw rolls, havebeen found to be particularly suitable. Such devices must allow for theaccurate adjustment and maintenance of the low degrees of tension whichare necessary to provide a relatively low load. After the drawing step,the yarn maybe completely released of tension and taken off oraccumulated in a tensionless condition. However, as a rule it is usuallymore convenient to guide the treated yarn, after the second set of drawrolls, over an additional takeoff device behind which a traversingdevice can be arranged.

The handling of the yarn between the second set of draw rolls and thetakeofi' device may be varied within wide limits. Thus, for example, itis possible to release the tension in the treated yarn completely oronly partially, so that the elastic strain and, where appropriate, thecrimp, is able to relax or reform entirely or partially. In thissituation, the spreading out effect is produced in the yarn in thisrelaxing zone, the extent of this effect depending on the lessening ofthe tension. The elongation of the yarn according to the invention mayalso be accomplished in two stages, e.g., if the peripheral velocitiesof three roller units are in sequence v v and v then one maintainsrelative speeds in which v v v applies. In such a case, it is desirableto effect the major proportion of the elongation in the first drawingzone. As soon as the yarn has left the last guide means, the completespreading apart to form the nonwoven yarn structure of greater widthtakes place as already mentioned. At the same time, the crimping arcsagain jump" back into position, i.e., the crimped structuresimultaneously reappears.

In the accompanying drawings:

FIG. 1 is a partially schematic side elevational view of apparatus whichis suitable for carrying out the process of the invention;

FIG. 2 is a perspective view of a coiled fleece web as one preferredtype of nonwoven product obtained by the process of the invention; and

FIG. 3 is an enlarged perspective view of a small section of anothertype of nonwoven product obtained by the process of the invention.

The process of the invention will now be explained in detail by anexample taken with reference to FIG. 1 of the accompanying drawing.

EXAMPLE Polyethylene terephthalate having a solution viscosity (1 of I.60, measured as a l percent solution of the polymer in mcresol at 25C., is spun through a l-aperture nozzle or spinning head to produce ahollow tubular filament yarn. The yarn is drawn, i.e., stretched, in aconventional manner under an atmosphere of steam maintained at C. (drawratio l:4. l and the stretched filaments are subsequently crimped in astuffing box. The resulting yarn exhibits the following properties:

Strength 47.7 Rhm. (5.3 g./den.)

Elongation 45 percent Hollow volume approximately 12 percent Individualtiter= 5.5 denier Crimping are number I00 arcs per 10 cm.

(The crimping are number is counted on a large number of filamentlengths which have been loaded with a weight of 3 mg., the observed arcsbeing those variations considered to be any marked change in direction;i.e., a sine curve would correspond to two crimping arcs).

Referring now to FIG. I, this initial polyester crimped yarn is fed froma supply container 1, via a torsion bar brake 2 and the deflecting rods3 and 4 to a set of three rollers 6. Arranged just before the latter isa yarn guide 5 which is particularly advantageous for the purpose ofinitially spreading out or positioning a large number of individualfilaments into a web or band of minimum width. The peripheral velocityof the rollers of the set of three rollers 6 is 60 m/min. The yarn iselongated between the triple roller arrangement 6 and a second morerapidly rotating triple roller arrangement 7, by between 8 percent andI0 percent. The tension applied by this drawing operation corresponds toa loading of 0.75 g./den. After leaving the triple rollers 7, the yarnis then guided over two rods 8 to a pair of rollers 9, the peripheralvelocity of which corresponds to that of the triple roller arrangement7. Behind or after the pair of rollers 9, the yarn quickly spreads outwith a complete release of tension to form a nonwoven fibrous web orfleece having a width of approximately 55 cm. and is deposited, by meansof a simple traversing device 10 in a collecting carton-or box 11.

Instead of the receiving container I1 shown in FIG. I, it is alsopossible of course to use other collecting or takeup devices. Thus, forthe manufacture of a filler for cushions, pillows or pads, the nonwovenfibrous web is wound loosely, e.g., on a reel or spindle either from thesupply container shown or directly after leaving the takeoff rolls 9 asdescribed. The nonwoven web or fleece may also be deposited in a numberof relatively flat layers one above the other. The filling elements forcushions or the like, which are manufactured in this way and illustratedby way of example in FIG. 2 of the when the nonwoven fibrous fleeces areused in coiled form or as a number of layers, it is possible by inwardlyfolding the front or end portions of the nonwoven fibrous web to preventany of the free filament ends from being disposed on the surface of thefiller so that they cannot project through the covering or outer fabricof the filled article. However, even if such steps are not taken, anydanger that the yarn or filament ends might project through the coveringof a cushion or similar article is much less than when the fillingmaterial consists of staple fibers. FIG. 2 merely shows a cushionfilling in the form of a wound or coiled web of the fleece.

When manufacturing quilted articles, it is possible,

depending on the desired result, to use thicker or thinner nonwovenfibrous webs. For quilts or sleeping bags, for example, a number ofnonwoven yarn structures can be disposed in layers one above the other,whereas for protective and lightweight garments, thinner nonwovenfibrous webs are generally preferred. The filaments may all extendsubstantially in the same direction or they may form any desired angleswith each other by cross laying. FIG. 3 shows a sector of a filler for aquilted article, in a highly enlarged perspective view, which has beenformed by cross-laying of individual fleece bands or webs.

Further tests have shown that the procedure of the invention is alsoapplicable to a wide variety of nonwoven fibrous webs or fleecesproduced from other fiber-forming polymer or from mixtures of continuousthermoplastic crimped filaments. The nonwoven fleeces of the inventionare especially distinguished by a substantially complete absence ofbroken or otherwise severely distorted filaments aside from theintentional permanent crimping which retains practically its originalcapacity for crimp contraction. At the same time, one achieves a muchmore voluminous fleece or web than could have been expected from therelatively mild processing conditions of the invention.

On the other hand, the fleece webs of the invention are alsodistinguished by a good coherence, and if desired they can be furtherimpregnated with a bonding agent or otherwise bonded together to form amore rigid but highly flexible and porous fibrous structure.

We claim:

1. Process for the production of a nonwoven fleece from continuousfilaments of a synthetic fiber-forming polymer which comprises:subjecting a spun and stretched yam made of permanently crimpedindividual filaments having an individual titer of 0.5 to denier and acrimping arc number of from 50 to 150 arcs per l0 cm. to a temporaryelongation sufficient to bring the individual filaments within the rangeof their elastic strain under a load of at least 0.l grams/denier; andthen releasing the tension on the yarn sufficiently to refonn thecrimped structure of the individual filaments and to permit said yarn tospread out laterally.

2. A process as claimed in claim 1 wherein said yarn is made ofpolyethylene terephthalate filaments.

3. A process as claimed in claim 2 wherein the permanent extensionproduced by said elongation of the yarn within the range of elasticstrain is less than 4 percent.

4. A process as claimed in claim 1 wherein the individual filament titeris between about 3 and 8 denier.

5. A process as claimed in claim 1 wherein the crimping are number isbetween about 65 and arcs per 10 cm.

6. A process as claimed in claim 1 wherein said yarn is made from hollowtubular filaments in which the hollow volume amounts to about 10 to 30percent of the total volume of each individual filament.

7. A process as claim 6 wherein said hollow tubular filaments arepolyethylene terephthalate filaments.

8. A process as claimed in claim 7 wherein the permanent extensionproduced by said elongation within the range of elastic strain is lessthan 3 percent.

9. A process as claimed in claim 1 wherein the yarn made from hollowtubular filaments of polyethylene terephthalate is subjected toelongation under a load of between about 0.1 and l g./den. and thehollow volume is about 10 to 30 percent of the total volume of eachindividual filament.

10. A process as claimed in claim 9 wherein the hollow volume is betweenabout 12 and 25 percent of the total volume of each individual filament.

11. A process as claimed in claim 9 wherein said elongation of the yarnis carried out under a load of between about 0.5 and 0.8 g./den.

12. A process as claimed in claim 9 wherein said filaments have anindividual titer of between about 3 and 8 denier.

13. A process as claimed in claim 12 wherein the permanent extensionproduced by said elongation of the yarn within the range of elasticstrain is less than 1.5 percent.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. D t d13,

Helmut Werner et al. Inventor(s) It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, lines 68 and 69, "'elastic e1ongati0n" shoL read "elasticstrain" is also sometimes referred to as the "elastic elongation" Signedand sealed this 17th day of August 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, Attesting OfficerCommissioner of Paten

2. A process as claimed in claim 1 wherein said yarn is made ofpolyethylene terephthalate filaments.
 3. A process as claimed in claim 2wherein the permanent extension produced by said elongation of the yarnwithin the range of elastic strain is less than 4 percent.
 4. A processas claimed in claim 1 wherein the individual filament titer is betweenabout 3 and 8 denier.
 5. A process as claimed in claim 1 wherein thecrimping arc number is between about 65 and 120 arcs per 10 cm.
 6. Aprocess as claimed in claim 1 wherein said yarn is made from hollowtubular filaments in which the hollow volume amounts to about 10 to 30percent of the total volume of each individual filament.
 7. A process asclaim 6 wherein said hollow tubular filaments are polyethyleneterephthalate filaments.
 8. A process as claimed in claim 7 wherein thepermanent extension produced by said elongation within the range ofelastic strain is less than 3 percent.
 9. A process as claimed in claim1 wherein the yarn made from hollow tubular filaments of polyethyleneterephthalate is subjected to elongation under a load of between about0.1 and 1 g./den. and the hollow volume is about 10 to 30 percent of thetotal volume of each individual filament.
 10. A process as claimed inclaim 9 wherein the hollow volume is between about 12 and 25 percent ofthe total volume of each individual filament.
 11. A process as claimedin claim 9 wherein said elongation of the yarn is carried out under aload of between about 0.5 and 0.8 g./den.
 12. A process as claimed inclaim 9 wherein said filaments have an individual titer of between about3 and 8 denier.
 13. A process as claimed in claim 12 wherein thepermanent extension produced by said elongation of the yarn within therange of elastic strain is less than 1.5 percent.